PHYSICO-MECHANICAL PROPERTIES AND DESIGN OF DE-STONING MACHINE FOR SMALL SCALE RICE MILLS
The quality of local rice is a major concern for the future of the Nigerian rice sector. The major problem being the appearance and cleanliness of the rice delivered to the market. They are characterized by high percentage of impurities like husk and stones as well as under size/broken grains which reduces it economic value and makes it difficult to compete favourably with imported ones. Therefore, one of the important quality additions is reduction of contaminants especially stones to the barest minimum. In this research work, a rice grain destoning machine was designed based on the physical, mechanical and aerodynamic properties of rice. The average dimensions of three rice varieties; Kano, Zaria, and Mario in terms of length, width and thickness were found to be 7.038mm 2.193mm and 1.95mm. While the averages for aspect ratio, arithmetic mean, geometric mean, surface area and sphericity were found to be 3.6mm, 3.73mm, 3.07mm, 29.72mm2 and 0.4372. The calculated destoning efficiency was 80% at a speed of 284 rpm and feed rate of 94 kg/hr. It was observed that physical properties like surface area, sphericity, and geometric mean diameter of rice increased with increase in moisture content from 10% to 16% with a regression coefficient of (R2) values of 0.96, 0.86 and 0.95 respectively. However, porosity of rice decreased with increase in moisture content with a regression coefficient of (R2) = -0.97. It was recommended that for enhanced separation of rice from stones the sieve tilt angle should allow rice have enough resident time on the sieves.
Authors : Tashiwa, Y.I., Kabri, H.U., Umaru, A.B., Hong, A.H. and Mailabari, R.J.
Category : Open Access Volume (Issue) : 10(1) Date Uploaded : 23rd April 2024